THE CHROMOSOME MECHANISM AS A BASIS FOR 
MENDELIAN PHENOMENA . 1 
John H. Schaffner. 
The farther investigation proceeds, the more convincing be¬ 
comes the conviction that the proportional inheritance of char¬ 
acters of plants and animals has its basis in the chromatin of 
the nucleus. The remarkable parallelism between the activities 
of the complicated mechanism of nuclear division and the readily 
predicted phenomena of Mendelian inheritance easily dispels the 
allurements of any other hypothesis. 
When in 1897 2 the writer showed the qualitative division of 
the reduction or bivalent chromosomes in the megasporocyte of 
Lilium philadelphicum, it was even then clearly seen by a number 
of cytologists that such a division would have an important bear¬ 
ing on heredity. At the time, however, there was no way of 
determining in the cells of the lily studied whether the separating 
transverse halves of the long, twisted loops were actually individual 
descendants of previous univalents, and Mendelian principles and 
laws were still resting in the limbo of neglected scientific dis¬ 
coveries. The theory of qualitative division was not kindly 
received at the time altho the investigation on Lilium philadel¬ 
phicum showed not a single important break in the series until 
the complete segregation of the metakinesis stage. The weight 
of authority both in cytology and genetics was against such an 
explanation. My paper was begun with the following words:— 
“Altho a knowledge of the changes which take place in the re¬ 
duction nuclei of plants and animals is of the utmost importance, 
and will not doubt aid more than anything else in bringing about 
a correct interpretation of the facts of heredity, comparatively 
little has been done in this field, and the observations that have 
been reported disagree widely.” 
In 1899, Paulmier 3 reported a transverse or qualitative divi¬ 
sion for the first reduction karyokinesis while the second was 
represented to be equational. These results on Anasa tristis 
agreed with what I had observed in Lilium philadelphicum. It 
was one of a very few thoro investigations of the times unbiased 
by contrary current opinion on the subject. In June 1901, the 
writer published his paper on Erythronium in which a qualitative 
1. Contribution from the Botanical Laboratory of the Ohio State 
University, No. 88. 
2. Schaffner, John H. The Division of the Macrospore Nucleus. 
Bot. Gaz. 23: 430-452. 
3. Paulmier, F. C. The Spermatogenesis of Anasa tristis. Jour, of 
Morph. 15: 223-272. 
Schaffner, J. H. A Contribution to the Life History and Cytology of 
of Erythronium. Bot. Gaz. 31: 369-387. 
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